021 Voss 2h5f

COSMETIC TESTS ON HUMAN SKIN MODELS: REALITY AND VISIONS Werner Voss, Ilsabe Bunge and Claas Rueffer DERMATEST, Medical Research Company, Engelstrasse 37, 48143 Muenster, . Tel: +49-251-4882249. Fax: +49-251-4902727 E-mail: [email protected]

ABSTRACT Physiological measurements for efficacy in cosmetics are still debated and are often not reproducible. Skin models may solve a lot of these problems. We developed a huma 3D skin model and now we can demonstrate different histological and physiological effects in human skin. For future developments of cosmetics this will be a good and stable method for detecting new effects in cosmetics and pharmaceuticals products. In this model it is possible to compare histological, physiological and genetic parameters within a time of 4 weeks. This method could accelerate and quantify cosmetic tests on human skin. Physiological, histological and genetic results showing the influence of different ingredients and hazards on the tissue development are presented. It could be shown that several test procedures are possible using this model. This is a good way to make cosmetic testing faster, more reliable and results more comparable. We are busy developing more test set ups to widen the range of this model for cosmetic testing.

In vitro skin equivalents are composed of a highly differentiated, stratified epithelium which resides on top of a dermal matrix with incorporated living fibroblasts. Despite their simplified model-like character, organotypic skin equivalents are capable of a far-reaching recapitulation of the in vivo keratinocyte differentiation program. But in contrast to real skin the in vitro 3D skin models are quite short-lived. Nevertheless, for a limited time period skin models are capable of sustaining a constant pool of skin cells to keep their epidermal structure maintained. Most interestingly full thickness skin models permit the analysis of dermal influences on the epidermal tissue rejuvenation and differentiation process. Therefore 3D skin models are a tool to study effects on skin renewal and epidermal homeostasis. We use the Phenion® FT skin models with standardized media and conditions.

Control without active

Application of vitamin D3 day 3

Application of vitamin D3 day 4

Our intension for using this model was the detection of basic effects of cosmetic ingredients. As a result we can show that the proliferative activity of basal keratinocytes and fibroblasts can be modulated by external stimulation. When grown in basal medium without growth stimuli, cells in epidermis and dermis showed a basic cell cycle activity. Explicit stimulation of cell growth could be triggered by

application of growth supplements into culture media, which leads to a noticeable increase of cell proliferation activity in epidermis and dermis. On the other hand the increased proliferative activity of stimulated epidermal and dermal cells could be silenced again when an explicit pro-inflammatory milieu was created by addition of interleukin-1 alpha (IL-1a) into the culture media. As expected, the data revealed that the proliferative cell activity in skin equivalents reacts dynamically according to the type of stimulus. 3 D skin models offer the opportunity for a differentiated analysis of dermal and epidermal viability. We could prove this by incubation with Vitamin A and D3 substances in named concentrations with a markedly positive influence on tissue viability. Conclusion: 3 D skin models are useful tools to study cosmetic and medical active ingredients.They extend the possibilities of testing cosmetic effects. Keywords: human skin model, cosmetic tests, skin damage, skin care